Tolerance to cadmium of vesicular arbuscular mycorrhizae spores isolated from a cadmium-polluted and unpolluted soil

We carried out a trial to investigate if vesicular arbuscular (VA) mycorrhizae from a Cd-polluted soil can increase both their Cd tolerance and their influence on the host plant, compared with the same strain from unpolluted soil. Inocula (S0, S1 and S2, respectively), were prepared from soil containing 0, 10, 100 mg/kg Cd (T0, T1 and T2, respectively). Each inoculum was added to each soil giving nine treatments. The percentage infection of barley roots and the spore numbers decreased proportionally with increasing Cd concentration in soil. However, the S2 inoculum showed the highest capacity to colonise the barley roots. This inoculum also created the best biotic barrier against the movement of Cd from the roots to the shoot in the T2 soil. In the T1 soil, the S1 and S2 inocula were less efficient than the S0 inoculum, probably because the level of soil pollution was not sufficiently high for any difference to be seen. We concluded that VA mycorrhizae can adapt to heavy metals and that their performance can influence metal translocation in the plant, providing a biological barrier. This is very important for the use of VA mycorrhizae in the reclamation of polluted soils.[PUBLICATION ABSTRACT]